Battery life only sort of bugs me, the real issue I have with modern batteries is longevity.
Once a typical Li-ion battery is a few years old it might as well be worthless, it will hold only a fraction of the original charge it could when it was new and that amount will continue to drop over time. If we could build batteries with even 80% of the storage density of Li-ion but would retain 90% of that capacity over 10 years I'd be pretty happy.